Chemical and electronic characterization of cobalt in a lanthanum perovskite. Effects of strontium substitution

Hueso, José L.; Holgado, Juan P.; Pereñíguez, Rosa; Mun, Simon; Salmerón, Miquel; Caballero, A.

doi:10.1016/j.jssc.2009.10.008

Cited by 40 publications

(28 citation statements)

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“…The doping leads to a metallic behaviour with ferro-magnetic interactions, see [11] and references therein. The electronic conductivity is further enhanced by an increase in the hybridization of the Co3d-O2p orbitals due to an increase in the mean Co-O-Co bonding angle towards 180° as the larger Sr 2+ ions replace La 3+ ions [29]. The formed oxygen vacancies improve the mobility of the oxygen ions and La 1-x Sr x CoO 3 is a mixed electronic and ionic conductor, an essential property for its use in SOFC electrodes or oxygen separating membranes [30].…”

Section: Introductionmentioning

confidence: 99%

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Phase formation, crystal structures and magnetic properties of perovskite-type phases in the system La2Co1+z(MgxTi1−x)1−zO6

Shafeie

Grîns

Istomin

et al. 2011

Journal of Solid State Chemistry

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Perovskite-type cobaltates in the system La 2 Co 1+z (Mg x Ti 1-x ) 1-z O 6 were studied for z = 0 ≤ x ≤ 0.6 and 0 ≤ x < 0.9, using X-ray and neutron powder diffraction, electron diffraction (ED), magnetic susceptibility measurements and X-ray absorption nearedge structure (XANES) spectroscopy. The samples were synthesised using the citrate route in air at 1350°C. The space group symmetry of the structure changes from P2 1 /n via Pbnm to c R3 with both increasing Mg content and increasing Co content. The

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Section: Introductionmentioning

confidence: 99%

“…The effects of the substitution of Co by Ti upon the electronic structure and magnetic properties are complex and have been discussed in detail by many authors [11,29,35]. Álvarez-Serrano et al [34] [15,36].…”

Section: Introductionmentioning

confidence: 99%

Phase formation, crystal structures and magnetic properties of perovskite-type phases in the system La2Co1+z(MgxTi1−x)1−zO6

Shafeie

Grîns

Istomin

et al. 2011

Journal of Solid State Chemistry

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“…Recently, we have demonstrated that the oxidation of carbon particles towards CO 2 is enhanced in the presence of cobaltites [8]. We have also shown that perovskite catalysts are very efficient for the oxidation of CO at low temperatures in a plasma-catalyst device [17] and [18].…”

Section: Introductionmentioning

confidence: 95%

“…The errors of these fittings have been estimated by using the following expression: (2) where n is the number of experimental measurements done between T 5 and T 95 (the temperatures of 5% and 95% conversion, respectively),%(T) represents the experimental conversion values and % F (T) represents the conversion values from the plots obtained after fitting. The results of these calculations are below 5% for the three cycles (Table 1), which demonstrates the accuracy of the fitting and the usefulness of the mathematical model.…”

Section: Near-ambient Xps and Correlation With Kineticsmentioning

confidence: 99%

“…The crystalline structure and the partial substitution of some of their cations by other elements with a different oxidation state confer to these compounds very interesting properties [2] and [3] and an enhanced activity for the oxidation of (unburned) hydrocarbons [4], [5] and [6], soot particles [7] and [8] or volatile organic compounds (VOCs) [9], [10] and [11]. The oxidation of carbon monoxide has been also extensively studied not only as a model gas to prove the adsorption sites over the perovskites [12], [13] and [14], but also because of its environmental impact as one of the most hazardous pollutants produced by mobile sources [15] and [16].…”

Section: Introductionmentioning

confidence: 99%

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Near-ambient X-ray photoemission spectroscopy and kinetic approach to the mechanism of carbon monoxide oxidation over lanthanum substituted cobaltites

Hueso

Martínez-Martínez

Caballero

et al. 2009

Catalysis Communications

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We have studied the oxidation of carbon monoxide over a lanthanum substituted perovskite (La 0.5 Sr 0.5 CoO 3−d ) catalyst prepared by spray pyrolysis. Under the assumption of a first-order kinetics mechanism for CO, it has been found that the activation energy barrier of the reaction changes from 80 to 40 kJ mol −1 at a threshold temperature of ca. 320 °C. In situ XPS nearambient pressure ( 0.2 torr) shows that the gas phase oxygen concentration over the sample decreases sharply at ca. 300 °C. These two observations suggest that the oxidation of CO undergoes a change of mechanism at temperatures higher than 300 °C.

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Strain‐Induced Orbital Contributions to Oxygen Electrocatalysis in Transition‐Metal Perovskites

Fernández

Caretta

Das

et al. 2021

Advanced Energy Materials

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B site have shown high activities and represent a cost-effective alternative to expensive noble metal-based catalysts; however, gas exchange at these perovskite surfaces remains the limiting factor for high efficiency in electrochemical devices. [1][2][3] The development of perovskites with high activity has historically relied on brute-force compositional screening involving the synthesis and testing of numerous bulk-ceramic samples to establish an intuition for chemical trends that can guide researchers to highly active compositions. More recently, however, there has been a significant push to develop electronic descriptors for predicting electrochemical activity. [4][5][6][7] This work has led to the identification of several electronic descriptors that are closely correlated with high activity for ORR and OER catalysts, including the relative position of the oxygen 2p band center, [6] the BO bond covalency, [8] and, in particular, the occupancy of the e g orbitals. [5,9] For example, e g orbital occupation has been shown to be strongly correlated with the B-site-dependent chemical activity trends, and an "ideal" e g occupancy of ≈1.2 electrons has been used as the justification for high activities in LaNiO 3 and Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) catalysts. [5,9,10] As such, the development of electronic descriptors has already proved fruitful in identifying compositions with high activities and, in turn, developing synthetic control of materials properties to tune the electronic structure toward these ideal values could unlock a new way to optimize materials.In parallel to the development of these electronic descriptors, researchers have leveraged thin-film-based studies to understand how manipulation of the lattice structure of these perovskites can affect the electrochemical activity. Several studies have focused on the role of epitaxial strain in perovskite oxides for controlling electrochemical activity. [11][12][13][14][15][16][17] Reports have noted enhanced electrochemical activities in cobalt-and ironbased perovskites under biaxial-tensile strain driven by straininduced changes to surface chemistry [12] or suggested electronic contributions as the driving force for enhanced electrochemical activity under tensile strain. [13,14,18] Meanwhile, strain-induced changes to e g occupancy have been proposed as the mechanism of enhanced ORR/OER activities in LaNiO 3 films under biaxial compressive strain. [16] This discrepancy suggests that straininduced changes to electronic structure may be dependent on the identity of the B-site cation and calls for more direct studies Epitaxial strain has been shown to produce dramatic changes to the orbital structure in transition metal perovskite oxides and, in turn, the rate of oxygen electrocatalysis therein. Here, epitaxial strain is used to investigate the relationship between surface electronic structure and oxygen electrocatalysis in prototypical fuel cell cathode systems. Combining high-temperature electricalconductivity-relaxation studies and synchrotron-...

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Chemical and electronic characterization of cobalt in a lanthanum perovskite. Effects of strontium substitution

Cited by 40 publications

References 28 publications

Phase formation, crystal structures and magnetic properties of perovskite-type phases in the system La2Co1+z(MgxTi1−x)1−zO6

Phase formation, crystal structures and magnetic properties of perovskite-type phases in the system La2Co1+z(MgxTi1−x)1−zO6

Near-ambient X-ray photoemission spectroscopy and kinetic approach to the mechanism of carbon monoxide oxidation over lanthanum substituted cobaltites

Strain‐Induced Orbital Contributions to Oxygen Electrocatalysis in Transition‐Metal Perovskites

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